Improvement in planinq-machines



' PLA NING-MACHINES.

No.1'84, Z99 Patented Nov. 14, 1876.

UNITED STATES PATENT @rrron.

DAVID HALL RICE, OF LOWELL, MASSACHUSETTS.

IMPROVEMENT lN PLANlNG-MACHINES.

Specification forming part of Letters Patent No. 184,299, dated November14 1876; application filed January 15, 1876.

To all whom it may concern:

Be it known that I, DAVID HALL Bron, of the city of Lowell, in thecounty of Middlesex and State of Massachusetts, have invented a new anduseful Improvement in Planing-Machines, of which the following is aspecification My improvement is made in the yielding spring shown in theEnglish patent of Burnett,.No. 7,926, dated January 8,1840, which springis there shown as extending or projecting under the planing-cylinder, tohold the board being planed down to. the bed of the machine against theaction of the cuttingcylinder. As heretofore used, this spring has beenof great stiffness, because, pwing to its tendency to yieldlongitudinally across the bed of the planer, but a small part, of theentire resiliency of the spring bore upon any one point. Hence theentire spring had to be made still enough to enable the amount of itsresiliency to produce the requisite pressure upon any raised or unequalpart of the surface of the board when it yielded longitudinally on itsedge. The result was, that when the surface of the board was perfectlylevel the pressure of thespring, owing to its stiffness, was greaterthan necessary. This difficulty'I have overcome by providing the flatspring with one or more flutings or corrugations, extending across itlongitudinally parallel, or nearly so, with the edge of the spring,which bears upon the board being planed.

I thus obviate the tendency of the spring to yield along this edge,while it yields in the other direction, as before, and this bringsnearly the entire pressure of the spring upon any inequality or raisedpart of the board, rendering its pressure upon this point moreefl'ective.

I am thus enabled to use a lighter spring to perform the required work,and thus diminish the average pressure upon the level part of the board.

In the drawings, Figure 1 is a longitudinal usual way.

Feed-rolls should be attached to the machine in the ordinary way; but Ihave not thought it necessary to show them, as their mode of attachmentand use is so Well known. On the cross-bars O G are attached the flatyielding springs F F, to hold the board down upon the platen by thepressure of their lower edges extending across the bed of the planer.

make these springs with one or more flutings or corrugations, S,extending longitudinally across them, parallel, or nearly so, with theiredges, which press upon the board. This renders them stilt: in thisdirection, but allows them to rise or yield to the inequalities of theboard, and brings the whole pressure of the spring to bear upon thepoint where needed. The flutings S may be applied to each spring in suchnumber and size and form, and as near the sired.

I have shown the springs at some distance from the line of cut of theknives; but they may be brought nearer to it, if desired. E is thedriving-pulley of the cylinder.

What I claim as new and of my invention is In combination with thebedand cutters of a planing.- machine, the spring F, provided with one ormore flutes or corrugations, extending across it parallel, or nearly so,with its pressing-edge, substantially as described.

DAVID HALL RICE. Witnesses l G. E. PRATT, A. K. GARLAND.

pressing-edge, as dc--

